Solid state light source device, automotive lighting using same, image display device, and drive method for solid state light source device

ABSTRACT

A solid state light source device includes N (an integer of two or more) sets of solid state light source assemblies having a plurality of solid state light source cells arranged in a matrix pattern a multiple lens block including N incidence faces facing the N sets of solid state light source assemblies and causing light emitted from the solid state light source cells to be incident through multiple lens cells of a matrix pattern and one emission face composing the light incident from the N incidence faces and a dichroic filter that is obliquely arranged on the incidence faces inside the multiple lens block and selectively reflects or transmits incident light based on the incident light wavelength. Light distribution characteristics and color temperature of light exiting the emission face of the multiple lens block are controlled by a ratio of power supplied to the solid state light source cells.

TECHNICAL FIELD

The present invention relates to a solid state light source device suchas a light emitting diode (LED), an automotive lighting using the solidstate light source device, an image display device, and a drive methodfor a solid state light source device.

BACKGROUND ART

In recent years, for a light source of an image display device that isone of an optical application device and a head lamp of a vehicle, anLED light source and a laser light source having superior powerconsumption efficiency and a long product life are used. Particularly,the LED light source has restrictions of the operating environment(temperature and humidity) less than the laser light source and a stableoperation and becomes the mainstream.

An LED having high output as a light source of an image display device,generally, is a surface emission light source and cannot collect lightinto an image display element that is a light receiving unit with highefficiency based on a conservation law of etendue (Etendue=emission areaof light source×divergence angle) in a case where the LED is used for alighting optical system. For this reason, a light source system having anew configuration has been proposed in which a laser light source havinga small area of a light emission portion and superior straightness as aprimary light source emits laser to a fluorescent substance forexcitation so as to acquire light (see Patent Documents 1 and 2).

On the other hand, in recent automotive lightings, a configuration inwhich an LED is used as a light source, and light distributioncharacteristics are controlled using an optical lens formed usingplastic and a reflector (reflecting mirror) becomes the mainstream (seePatent Document 3).

CITATION LIST Patent Document

Patent Document 1: JP 2011-158502 A

Patent Document 2: JP 2013-114980 A

Patent Document 3: JP 2008-41557 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Each of image display devices described in Patent Documents 1 and 2includes: an image display element; a lighting optical system that emitslight of a light source device to the image display element; and aprojection lens that enlarges and projects an optical image. Here, thelighting optical system has been contrived not to cause an increase inthe size of a light source device when the light source device thatcollects luminous fluxes from a plurality of light sources into oneluminous flux and then emits the luminous flux to a lighting systemdisposed on the latter stage is used.

More specifically, in Patent Document 1 (FIG. 1), one or more lightsources (laser light sources) 300P and 300S having a polarization degreeof 50% or more as light sources used for excitation and one or morepolarizers 23 transmitting polarized light of one side and reflectingpolarized light of the other side are included, and, by combining twosets of laser light having mutually-different polarization directions,excitation light sources that are compact and have high output areformed, and the laser light is collected into a fluorescent substancewith which a transparent base material 190 disposed on a later stage iscoated, by using a condensing lens 140. As a result, luminous fluxesemitted from the fluorescent substance can be caused to be incident to alighting optical system of a later stage more efficiently, in otherwords, without increasing the etendue described above.

Similarly, in Patent Document 2 (FIG. 1), light source units (laserlight sources) 10 and 20 having mutually-different polarizationdirections as light sources used for excitation and a composition unit30 transmitting polarized light of one side and reflecting polarizedlight of the other side are included, and, by combining two sets oflaser light having mutually-different polarization directions,excitation light sources that are compact and have high output areformed, and the laser light is collected into a fluorescent substancewith which a light emitting device 80 of a later stage is coated, byusing a superposition optical system 70.

However, in the technologies disclosed in Patent Documents 1 and 2,since the laser light sources are used as light sources, there arerestrictions on the operating environments (temperature and humidity),and there are cases where the operation is not stable. In addition, itis not considered to freely control the light distributioncharacteristics or the color temperature of emitted light.

Meanwhile, in Patent Document 3 (FIG. 2), a lighting unit formed ofplastic that is configured by: a light emitting unit 8 (white LED); areflector formed by a plurality of reflection surfaces M1, M2, M3, andM4; and a shade face S has been disclosed as an automotive lighting. Thelight emitting unit 8illustrated here is a light source having an area,has a large value of the etendue described above, and includes fourreflection surfaces. Thus, it is difficult to easily control optimallight distribution characteristics. In addition, the light emitting unit8 is a white LED and cannot freely control the color temperature oflight transmitted from the lighting.

The present invention is in consideration of the problems describedabove, and an object thereof is to provide a solid state light sourcehaving high light emission efficiency and being capable of freelycontrolling the color temperature. In addition, another object is toprovide an automotive lighting capable of easily acquiring desired lightdistribution characteristics.

Solutions to Problems

In order to solve the problems described above, according to the presentinvention, there is provided a solid state light source deviceincluding: N (here, N is an integer of two or more) sets of solid statelight source assemblies in which a plurality of solid state light sourcecells are arranged in a matrix pattern; a multiple lens block thatincludes N incidence faces facing the N sets of solid state light sourceassemblies and causing light emitted from the solid state light sourcecells to be incident through multiple lens cells of a matrix pattern andone emission face composing the light incident from the N incidencefaces and causing composed light to exit through multiple lens cells ofa matrix pattern; and a dichroic filter that is obliquely arranged onthe incidence faces inside the multiple lens block and selectivelyreflects or transmits incident light based on a wavelength of theincident light, wherein light distribution characteristics and a colortemperature of light exiting from the emission face of the multiple lensblock to a light receiving unit are configured to be controlled bycontrolling a ratio of power supplied to the solid state light sourcecells.

In addition, according to the present invention, there is provided anautomotive lighting using a solid state light source device including: areflector that reflects light exiting from the solid state light sourcedevice, wherein the solid state light source device is configured toinclude a solid state light source assembly in which a plurality ofsolid state light source cells that are light emitting points arearranged in a matrix pattern, the solid state light source cells areconfigured to be formed by combining solid state light source cellshaving light emission colors including light's three primary colors, andlight exiting from a plurality of the solid state light source cells isconfigured to be incident to different positions in the reflector.

Furthermore, according to the present invention, there is provided animage display device using a solid state light source device including:an image display element that forms image light by emitting lightexiting from the solid state light source device; and a projection lensthat projects the image light formed by the image display element in anenlarged scale, wherein the solid state light source device isconfigured to include a solid state light source assembly in which aplurality of solid state light source cells that are light emittingpoints are arranged in a matrix pattern, and the solid state lightsource cells are configured to be formed by combining solid state lightsource cells having light emission colors including light's threeprimary colors.

In addition, according to the present invention, there is provided adrive method for a solid state light source device using solid statelight sources as light emitting bodies, wherein it is configured suchthat illumination acquired in a desired light receiving unit by usinglight emitted from the solid state light source device is 170 lux ormore, a drive current of the solid state light sources has a pulsewaveform, and a frequency of the pulse is 60 Hz or more.

Effects of the Invention

According to the present invention, a solid state light source havinghigh light emission efficiency and being capable of freely controllingthe color temperature can be provided. In addition, an automotivelighting capable of easily acquiring desired light distributioncharacteristics can be provided. Furthermore, driving of a solid statelight source enabling a user not to feel flicker with a drive currentsuppressed but to have a visually bright feeling can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view that illustrates a solid state light sourcedevice according to a first embodiment.

FIG. 2 is a plan view that illustrates a solid state light source deviceaccording to the first embodiment.

FIG. 3 is a perspective view that illustrates a solid state light sourcedevice according to a second embodiment.

FIG. 4 is a plan view that illustrates a solid state light source deviceaccording to the second embodiment.

FIG. 5 is a plan view that illustrates a solid state light source deviceaccording to a third embodiment.

FIG. 6 is a plan view that illustrates a solid state light source deviceaccording to a fourth embodiment.

FIG. 7 is a plan view that illustrates a solid state light source deviceaccording to a fifth embodiment.

FIG. 8 is a plan view that illustrates a solid state light source deviceaccording to a sixth embodiment.

FIG. 9 is a plan view that illustrates a solid state light source deviceaccording to a seventh embodiment.

FIG. 10 is a plan view that illustrates a solid state light sourcedevice according to an eighth embodiment.

FIG. 11 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a ninthembodiment.

FIG. 12 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a tenthembodiment.

FIG. 13 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to aneleventh embodiment.

FIG. 14 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a twelfthembodiment.

FIG. 15 is a plan view that illustrates an image display device, towhich a solid state light source device is applied, according to athirteenth embodiment.

FIG. 16 is a diagram that illustrates the configuration of apolarization conversion element.

FIG. 17 is a diagram that illustrates the transmittance of a P wave andthe transmittance of an S wave on a PBS surface of a polarizationconversion element.

FIG. 18 is a characteristic diagram that illustrates the reflectance ofeach material with respect to an incidence angle.

FIG. 19 is a diagram that illustrates a relation between a lighting timeand a feeling of brightness felt by a human.

FIG. 20 is a diagram that illustrates a relation between a lightingfrequency and a feeling of flicker felt by a human.

FIGS. 21A and 21B are diagrams that illustrate a result of a visualevaluation of pulse drive.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

[First Embodiment]

FIGS. 1 and 2 are diagrams that illustrate the configuration of a solidstate light source device according to a first embodiment of the presentinvention, FIG. 1 is a perspective view, and FIG. 2 is a plan view.Hereinafter, a same reference numeral is assigned to components thatsimilarly function.

The solid state light source device 1 includes: a solid state lightsource assembly 11 in which a plurality of solid state light sourcecells corresponding to green are arranged; a solid state light sourceassembly 12 in which a plurality of solid state light source cellscorresponding to blue and red are arranged; and two multiple lens blocks21 and 22 in which a plurality of multiple lens cells are arranged in amatrix pattern. The multiple lens blocks 21 and 22 have a cross-sectionof a rectangular equilateral triangular shape, and the hypotenusesthereof are joined together through a dichroic filter 25. The solidstate light source assembly 11 and the solid state light source assembly12 are arranged to face two side faces of the multiple lens blocks 21and 22.

In the solid state light source assembly 11, a plurality of (here, four)solid state light source cells 111, 112, 113, and 114 are arranged in amatrix pattern (2×2), and each of the solid state light source cells isconfigured by an LED that emits green light (the solid state lightsource cell 114 is not illustrated in the drawing). In order to decreasethe etendue, the area of the light emitting portion of each solid statelight source cell is configured to be 0.5 mm² or less. More preferably,by configuring the area of the light emitting portion to be 0.1 mm² orless, the lighting efficiency can be further increased.

In order to collect luminous fluxes emitted from the light emittingportion in a desired direction, an optical device (represented as aconvex lens in FIG. 2) used for collecting light is arranged near thesolid state light source.

On the other hand, in the solid state light source assembly 12, aplurality of (here, four) solid state light source cells 121, 122, 123,and 124 are arranged in a matrix pattern (2×2), the solid state lightsource cells 121 and 124 are configured by LEDs emitting blue light, andthe solid state light source cells 122 and 123 are configured by LEDsemitting red light. Also for these, in order to decrease the etendue,the area of the light emitting portion of each solid state light sourcecell is configured to be 0.5 mm² or less (more preferably, 0.1 mm² orless).

The multiple lens block 21 faces the solid state light source assembly11, and multiple lens cells 211 to 214 are arranged in a matrix patternat positions facing the solid state light source cells 111 to 114 (themultiple lens cells 213 and 214 are not illustrated). The multiple lensblock 22 faces the solid state light source assembly 12, and multiplelens cells 221 to 224 are arranged in a matrix pattern at positionsfacing the solid state light source cells 121 to 124 (the multiple lenscells 223 and 224 are not illustrated). On an emission face of themultiple lens block 22, multiple lens cells 225 to 228 are furtherarranged in a matrix pattern.

The dichroic filter 25 selectively reflects or transmits incident lightbased on the wavelength of the incident light. Here, light of a greenwavelength region is transmitted, and light of a red wavelength regionand light of a blue wavelength region are reflected. This dichroicfilter 25 may be disposed in each of the multiple lens blocks 21 and 22or may be disposed alone in one of the multiple lens blocks. In any ofthe cases, the dichroic filter is interposed between two multiple lensblocks and is obliquely arranged on the incidence face (side face).While the two multiple lens blocks 21 and 22 are configured to have abonding structure having advantages of improved assembly precision, adecreased reflection surface, and the like, the multiple lens blocks maybe separate from each other.

Green luminous fluxes emitted from the solid state light source cells111 to 114 of the solid state light source assembly 11 are incident fromthe multiple lens cells 212 to 214 of the multiple lens block 21, aretransmitted through the dichroic filter 25, and exit from the multiplelens cells 225 to 228 of the multiple lens block 22.

Red/blue luminous fluxes emitted from the solid state light source cells121 to 124 of the solid state light source assembly 12 are incident fromthe multiple lens cells 222 to 224 of the multiple lens block 22, arereflected by the dichroic filter 25, and exit from the multiple lenscells 225 to 228.

The luminous fluxes exiting from the multiple lens cells 225 to 228 ofthe multiple lens block 22 are emitted to a light receiving unit 90 inan enlarged scale. The multiple lens cells 225 to 228 are formed to havesuch an aspect ratio so as to form a desired rectangular shape in thelight receiving unit 90. The luminous fluxes emitted from the solidstate light source assembly 11 and the solid state light source assembly12 are composed by the dichroic filter 25. For example, the luminousfluxes emitted from the solid state light source cell 111 are composedwith the luminous fluxes emitted from the solid state light source cell121 to be composite luminous fluxes A and are emitted to an area 90 a ofthe light receiving unit 90. The luminous fluxes emitted from the solidstate light source cell 112 is composed with the luminous fluxes emittedfrom the solid state light source cell 122 to be composite luminousfluxes B and are emitted to an area 90 b of the light receiving unit 90.Similarly, composite luminous fluxes C and D (not illustrated in thedrawing) are respectively emitted to areas 90 c and 90 d of the lightreceiving unit 90.

In the light receiving unit 90, enlarged images are individuallyacquired in the areas 90 a to 90 d corresponding to the compositeluminous fluxes, and thus, the brightness or the chromaticity can beindividually changed within the same light receiving unit 90. Forexample, by superimposing the green light emitted by the solid statelight source assembly 11 and the blue/red light emitted by the solidstate light source assembly onto the light receiving unit 90 at apredetermined color mixing ratio, white light can be acquired in eacharea. In addition, also by changing the color mixing ratio, variouscolors (color temperatures) appearing within a coordinate rangerepresented as three colors alone on a chromaticity diagram can berepresented.

According to this embodiment, by configuring the emission face of thesolid state light source to be 0.5 mm² or less, the etendue can bedecreased, and the light emission efficiency can be improved.Furthermore, by changing the mixing ratio of combined light of LED(solid state) light sources having a plurality of light emission colors,the color temperature of the emitted luminous fluxes can be freelycontrolled.

In addition, in this embodiment, while the solid state light sourceassembly 12 is configured by combining solid light source cells emittingblue light and solid state light source cells emitting red light, allthe solid state light source cells may be solid state light source cellshaving magenta as the light emission color.

[Second Embodiment]

FIGS. 3 and 4 are diagrams that illustrate the configuration of a solidstate light source device according to a second embodiment of thepresent invention, FIG. 3 is a perspective view, and FIG. 4 is a planview. Differences from the first embodiment described above are in thata polarization conversion element 30 is disposed between a multiple lensblock 22 and a light receiving unit 90, and luminous fluxes areconfigured to be superimposed in the light receiving unit 90 after thepolarization directions of light exiting from the multiple lens block 22are aligned.

For example, green luminous fluxes emitted from a solid state lightsource cell 111 of a solid state light source assembly 11 are collectedby a multiple lens cell 211 of a multiple lens block 21 that isoppositely arranged and are enlarged and exit from a multiple lens cell225 disposed in a corresponding multiple lens block 22. The luminousfluxes that are enlarged and exit from the multiple lens 225 areincident to the polarization conversion element 30 and are projected tothe light receiving unit 90 in an enlarged scale as light of which thepolarization direction is aligned.

FIG. 16 is a diagram that illustrates the configuration of thepolarization conversion element 30. The polarization conversion element30 aligns the polarization states of luminous fluxes A to D exiting frommultiple lens cells 225 to 228 and has a configuration in which aplurality of polarization conversion cells 300 are arranged in parallelwith one-to-one matching with the multiple lens cells 225 to 228. Theluminous fluxes (a two-dimensional light source image of the solid statelight source) exiting from the multiple lens cells 225 to 228 areincident to an incidence area 301 of a corresponding polarizationconversion cell 300.

In each polarization conversion cell 300, a polarized beam splitter film302 (hereinafter, referred to as a PBS film) as a polarization splitterfilm and a phase difference plate 303 are included. The PBS film 302splits luminous fluxes (a P wave and an S wave are mixed), which arenon-polarized state, incident to the incidence area 301 by transmittingthe P wave and reflecting the S wave. The P wave is transmitted throughthe PBS film 302 and has the polarization direction converted into an Swave by the phase difference plate 303 and exit. On the other hand, theS wave is reflected by the PBS film 302 and is reflected again by aneighboring PBS film 302 arranged to be approximately parallel and exitwith maintained as an S wave. As a result, luminous fluxes having thepolarization direction aligned in the S wave can be acquired.

FIG. 17 is a diagram that illustrates the transmittance of a P wave andthe transmittance of an S wave on a PBS plane of a general polarizationconversion element. The transmittance (or the reflectivity) of the Pwave and the S wave depends on the incidence angle and the wavelength.The transmittance of a P wave of the green wavelength region markedlydecreases as the incidence angle deviates from an incidence angle of 45degrees by ±2 degrees. Meanwhile, similarly, the transmittance of an Swave of the blue wavelength region markedly decreases as the incidenceangle deviates from an incidence angle of 45 degrees by ±2 degrees. Forthis reason, in this embodiment, a telecentric optical system is usedsuch that the beam incidence angle on a reflection surface on which thePBS film 302 is disposed is in a desired range.

In the second embodiment, luminous fluxes exiting from one multiple lenscell have optical paths split into a P wave and an S wave by thepolarization conversion element 30. Accordingly, in the light receivingunit 90, all the luminous fluxes enlarged by the multiple lens cell aresuperimposed (represented as a composite luminous flux E), andillumination light having uniform brightness for the whole face of thelight receiving unit 90 can be acquired.

At that time, by combining a plurality of multiple lens blocks in whichmultiple lens cells having a plurality of lens functions incorrespondence with the solid state light source cells are arranged in amatrix pattern, the polarization directions can be aligned to a constantdirection without decreasing the beam passing ratio of the polarizationconversion element 30.

In addition, also in the second embodiment, by superimposing lightemitted by the solid state light source assembly 11 emitting green lightand light emitted by the solid state light source assembly 12 emittingblue light and red light onto the light receiving unit at apredetermined color mixing ratio, white light can be acquired. Inaddition, it is apparent that, by changing the color mixing ratio,various colors (color temperatures) appearing within a coordinate rangerepresented as three colors alone on a chromaticity diagram can berepresented.

[Third Embodiment]

FIG. 5 is a plan view that illustrates a solid state light source deviceaccording to a third embodiment of the present invention. In thisembodiment, light shielding plates 41 and 42 are added to the exit sideof the solid state light source cell in the configuration according tothe second embodiment (FIG. 4) described above. By arranging the lightshielding plates 41 and 42, return light (stray light) returning to thesolid state light source cell is decreased, and there are effects ofsecuring a life of the solid state light source and reducing the adverseinfluence of the stray light on the light source light.

[Fourth Embodiment]

FIG. 6 is a plan view that illustrates a solid state light source deviceaccording to a fourth embodiment of the present invention. According tothis embodiment, in the configuration according to the second embodimentdescribed above (FIG. 4), in each of the solid state light source cells111, 112, . . . , not a convex lens but a diffractive lens is arrangedas an optical device. The diffractive lens can be optimally designed ina case where the wavelength region of the light source is a narrow band,and the refractive power can be relatively freely controlled bysuppressing a diffractive loss. Accordingly, the diffractive lens isappropriate for controlling the directivity of the solid state lightsource.

[Fifth Embodiment]

FIG. 7 is a plan view that illustrates a solid state light source deviceaccording to a fifth embodiment of the present invention. According tothis embodiment, in the configuration of the first embodiment (FIG. 2)described above, each of the solid state light source cells 111, 112, isconfigured by a plurality of solid state light sources. Each solid statelight source cell illustrated in FIG. 7 is configured to include 3×3=9solid state light sources. According to this, also in the multiple lensblocks 21 and 22, the multiple lens cell is arranged to face eachindividual light source. As a result, a plurality of composite luminousfluxes corresponding to the number of solid state light sources areemitted to the light receiving unit 90.

[Sixth Embodiment]

FIG. 8 is a plan view that illustrates a solid state light source deviceaccording to a sixth embodiment. According to this embodiment, in theconfiguration of the first embodiment (FIG. 2), three solid state lightsource assemblies 11, 12, and 13 are included. The solid state lightsource assembly 11 is configured by solid state light source cells 111,112, . . . , emitting green light, the solid state light source assembly12 is configured by solid state light source cells 121, 122, . . . ,emitting red light, and the solid state light source assembly 13 isconfigured by solid state light source cells 131, 132, . . . , emittingblue light. In addition, three multiple lens blocks 21, 22, and 23 andan exit-side multiple lens block 24 are disposed to face such solidstate light source assemblies. Then, on the bonding face of the fourmultiple lens blocks, two dichroic filters 25 and 26 are arranged. Lightof three colors emitted from the solid state light source assemblies 11,12, and 13 are composed together by the multiple lens blocks 21, 22, 23,and 24 and are emitted to a light receiving unit 90.

At this time, by controlling the emission amounts of the green solidstate light source assembly 11, the red solid state light sourceassembly 12, and the blue solid state light source assembly 13 andsuperimposing the light onto the light receiving unit 90 at apredetermined color mixing ratio, desired white light can be acquiredfor each area. In addition, by changing the color mixing ratio, variouscolors (color temperatures) appearing within a coordinate rangerepresented as three colors alone on a chromaticity diagram can berepresented. Furthermore, similar to the first embodiment, in the lightreceiving unit 90, an enlarged image is individually acquired in eacharea in correspondence with each composite luminous flux, andaccordingly, the brightness and the chromaticity can be individuallychanged within the same light receiving unit 90.

[Seventh Embodiment]

FIG. 9 is a plan view that illustrates a solid state light source deviceaccording to a seventh embodiment of the present invention. According tothis embodiment, in the configuration of the sixth embodiment (FIG. 8)described above, a superposition lens 50 is arranged between a multiplelens block 24 and a light receiving unit 90. The superposition lens 50can efficiently superimpose light exiting from the multiple lens block24 onto the polarization conversion element 30 and the light receivingunit 90. Accordingly, the solid state light source device is appropriateas a light source device of an image display device or the like.

[Eighth Embodiment]

FIG. 10 is a plan view that illustrates a solid state light sourcedevice according to an eighth embodiment of the present invention.According to this embodiment, in the configuration of the seventhembodiment (FIG. 9) described above, a luminous flux conversion mirror55 is arranged between a multiple lens block 24 and a polarizationconversion element 30, and an optical path from the polarizationconversion element 30 to a light receiving unit 90 is converted into aperpendicular direction.

The luminous flux conversion mirror 55 has a function for collectingluminous fluxes exiting from the multiple lens block 24. For thisreason, the shape of the surface of the luminous flux conversion mirror55 has a cross-section, which has a cylindrical axis in the long axisdirection (a depth direction of the drawing) of the polarizationconversion element 30, having a concave face (cylindrical face) shape.As a result, since the beam passing ratio of the polarization conversionelement 30 is improved, a light source device having high lightutilization efficiency can be acquired.

In addition, by using the superposition lens 50 arranged between thepolarization conversion element 30 and the light receiving unit 90, thebeam incidence angle for the light receiving unit 90 is controlled.Particularly, in a case where a transmission-type image display element(liquid crystal device) is used as the light receiving unit 90, the beamincidence angle can be decreased also in the vicinity of the displayscreen, and accordingly, a bright image having superior contrastperformance can be acquired.

The solid state light source devices according to the first to eighthembodiments described above can be applied to an automotive lighting(headlight) or a light source of an image display device to be describedbelow.

[Ninth Embodiment]

FIG. 11 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a ninthembodiment of the present invention. The automotive lighting 2 isconfigured to acquire desired light distribution characteristics byreflecting luminous fluxes emitted from the solid state light sourcedevice 1 by using a reflector 70.

The light source luminous fluxes emitted from the solid state lightsource device 1 are incident to the reflector 70 from an obliquelyforward direction (optical axis L1), are reflected by the reflector 70,and exit to the front side as emission luminous fluxes (optical axisL2). Accordingly, the shape of the reflection surface of the reflector70 may be a spherical face that is symmetrical with respect to theoptical axes L1 and L2 or a free curved shape that can be designed morefreely than the aspherical shape.

In a case where the solid state light source device 1 emits light and avehicle does not travel, the temperature of the reflector 70 is near100° C. under warm weather. Accordingly, as the material of thereflector 70, a thermosetting resin having high heat resistance may beused. Alternatively, a thermoplastic resin having superiortransferability from a mold having the shape of a reflection surface ofthe reflector 70 may be used.

In a conventional automotive lighting, since there is a single lightemission point of a used light source, the light distributioncharacteristics depend only on the shape of a reflector, and thechromaticity of the reflection light (emitted light) is determined asthe emission color of the single light source. In contrast to this, inthe automotive lighting according to this embodiment, a plurality ofsolid state light source cells that are light emission points arepresent, and relative positions (incidence positions) between the solidstate light source cells and the reflector 70 are different from eachother. Accordingly, the degree of freedom for controlling the lightdistribution characteristics markedly increases. In addition, since thelight source color is formed by combining the solid state light sourcecells including light's three primary colors of green, red, and blue, adesired distributed light color distribution is acquired, and an effectnot present in the conventional technology can be acquired.

Meanwhile, by disposing the polarization conversion element 30 on theexit side of the solid state light source device 1, the polarizationdirections of exiting light are aligned, and the reflectance on thereflection surface of the reflector 70 is increased, whereby theintensity of the emitted light can be improved.

FIG. 18 is a characteristic diagram that illustrates the reflectance ofeach material with respect to an incidence angle. The reflectance of ametal reflection surface has dependency on an incidence angle based onthe polarization direction (an S wave or a P wave). As illustrated inFIG. 18, in terms of materials, aluminum (Al) has high reflectance, andS polarization has reflectance higher than P polarization as thepolarization direction. Accordingly, by using an Al film as thereflection film of the reflector 70 and aligning the polarizationdirections to the S polarization, the number of luminous fluxesreflected from the automotive lighting 2 increases, and an automotivelighting having high power consumption efficiency can be realized.

In addition, as can be understood from FIG. 18, metal such as copper(Cu) or glass (BSC-7) has high reflectance for the S polarization. Thismeans that light reflected from the body (a metal face or front glass)of a vehicle coming in the opposite direction is strong, andillumination light having superior visibility can be acquired also atthe luminous flux amount according to laws and regulations.

In addition, as a driver driving the vehicle wears polarizationsunglasses transmitting the polarized light described above, a secondaryeffect of acquiring a good field of view according to a lighting(headlight) disposed on his front side while reducing a visiondisturbance according to the headlight of a vehicle coming in theopposite direction can be acquired.

[Tenth Embodiment]

FIG. 12 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a tenthembodiment of the present invention. The automotive lighting 2 accordingto this embodiment is configured to reflect and emit luminous fluxesemitted from a solid state light source device 1 by using two reflectors71 and 72.

The light source luminous fluxes emitted from the solid state lightsource device 1 are formed as primary reflection luminous fluxes havinga desired luminous flux distribution by using the shape of thereflection surface of the first reflector and then are reflected by thesecond reflector 72 to be secondary reflection luminous fluxes (emittedluminous fluxes). According to this configuration, since two surfaces ofthe reflection face can be used, the degree of freedom of design ishigher than that according to the ninth embodiment (FIG. 11), the lightdistribution characteristics can be finely controlled, and excellentcharacteristics are acquired.

Also in this case, the primary reflection luminous fluxes from the firstreflector 71 are incident to the second reflector from an obliquelyforward direction (optical axis L2), are reflected by the secondreflector 72, and exit to the front side as emission luminous fluxes(optical axis L3). Accordingly, as the shape of the reflection surfaceof the second reflector 72, a free curved shape having a high degree offreedom of design may be selected. In addition, in this embodiment, thesolid state light source device 1 can be arranged in the sheet depthlength direction of the second reflector 72, and accordingly, the degreeof freedom of design of the whole shape of the automotive lighting 2 isfurther increased.

[Eleventh Embodiment]

FIG. 13 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to aneleventh embodiment of the present invention. According to theautomotive lighting 2 of this embodiment, in the automotive lighting 2according to the ninth embodiment (FIG. 11), the reflection surface ofthe reflector 70 is formed using a composite body including a pluralityof reflection surfaces. The plurality of reflection surfaces are incorrespondence with a plurality of luminous fluxes emitted from thesolid state light source device 1.

A plurality of luminous fluxes (denoted by arrows in the drawing)emitted from the solid state light source device 1 are respectivelyincident to corresponding reflection surfaces 70 a to 70 d of thereflector 70. Alternatively, a luminous flux emitted from one solidstate light source cell may be incident to a plurality of reflectionsurfaces. A plurality of emission luminous fluxes (represented byoptical axes La to Ld) reflected by the reflection surfaces 70 a to 70 dare emitted to the front side. Accordingly, illumination light havingdesired light distribution characteristics can be acquired.

While the emission directions (the optical axes La to Ld) from thereflection surfaces 70 a to 70 d may be set to a constant direction,there are also cases where the emission directions are set tomutually-different directions so as to acquire specific lightdistribution characteristics (light distribution). Particularly, on thereflection surfaces 70 c and 70 d disposed at positions close to thesolid state light source device 1, the range in which luminous fluxesemitted from the solid state light source device 1 is narrow, and thelight intensity per unit area is high. Accordingly, such reflectionsurfaces are appropriate for increasing the width of the emissionluminous fluxes for easy rough control of the light distributioncharacteristics. In addition, by setting the optical axes Lc and Ld ofthe reflection light to mutually-different directions, desired lightdistribution characteristics can be acquired. For example, by forming alight distribution for setting the optical axis Ld toward the outer sideof the vehicle by using the reflection surface 70 d positioned on theouter side of the vehicle, the obliquely forward side of the vehicle canbe efficiently irradiated.

On the other hand, on the reflection surfaces 70 a and 70 b disposed atpositions far from the solid state light source device 1, the range inwhich luminous fluxes emitted from the solid state light source device 1is wide, and the light intensity per unit area is low. Accordingly, finecontrol of the light distribution characteristics can be easilycontrolled, and such reflection surfaces are appropriate fordistributing light at a spot by narrowing the width of the luminousfluxes. In addition, by setting the optical axes La and Lb of thereflection light to mutually-different directions, desired lightdistribution characteristics can be acquired.

Furthermore, in this embodiment, in order to protect the solid statelight source device 1 and the reflector 70 from external atmosphere, alighting cover 80 is arranged so as to cover the reflection surfaces.While the shape of the lighting cover 80 may be a plastic shape having auniform thickness, the lighting cover may be configured to have a lensfunction so as to further control the light distribution characteristicsformed by the reflector 70.

[Twelfth Embodiment]

FIG. 14 is a diagram that illustrates the configuration of an automotivelighting using a solid state light source device according to a twelfthembodiment of the present invention. According to the automotivelighting 2 of this embodiment, in the automotive lighting 2 according tothe tenth embodiment (FIG. 12), the reflection surface of a secondreflector 72 is formed as a composite body including a plurality ofreflection surfaces. The plurality of reflection surfaces are incorrespondence with a plurality of luminous fluxes reflected from afirst reflector 71.

After luminous fluxes emitted from the solid state light source device 1are formed as primary reflection luminous fluxes having a desiredluminous flux distribution based on the shape of the reflection faces ofthe first reflector 71, the luminous fluxes are reflected by the secondreflector 72 so as to be secondary reflection luminous fluxes (emissionluminous fluxes). According to this configuration, the degree of freedomof design is increased for one surface, and accordingly, the lightdistribution characteristics can be controlled more finely than those ofthe eleventh embodiment (FIG. 13), and excellent characteristics can beacquired.

The shape of the reflection surfaces of the second reflector 72, similarto that of the eleventh embodiment (FIG. 13), includes a plurality ofreflection surfaces 72 a to 72 d. In this case, the shape is formed as afree curved shape continuously connecting the independent reflectionsurfaces 72 a to 72 d to which light split into a plurality of pieces oflight is incident, and the reflection surfaces are arranged such thatoptical axes La to Ld representing the reflection directions of thereflection surfaces face different directions in the plurality of thereflection surfaces. Accordingly, the emission directions of theplurality of the emission luminous fluxes are changed, and desired lightdistribution characteristics can be realized.

Since this embodiment has a configuration acquired by combining thetenth embodiment (FIG. 12) and the eleventh embodiment (FIG. 13), it isapparent that there are advantages of both the embodiments describedabove.

[Thirteenth Embodiment]

FIG. 15 is a plan view that illustrates an image display device, towhich a solid state light source device is applied, according to athirteenth embodiment of the present invention. Here, the diagram is aplan view that illustrates the configuration of a liquid crystal-typeprojection device as an example. In the liquid crystal-type projectionapparatus 3 illustrated here, illumination light generated by the solidstate light source device 1 is guided to dichroic mirrors 63 and 64through a polarization conversion element 61 and a weight lens 62. Thedichroic mirrors 63 and 64 split the illumination light into blue greenand red and emit the split illumination light to three liquid crystalpanels 65, 66, and 67 that are image display elements. The image lightof blue, the image light of yellow, and the image light of red arecomposed by a cross prism 68 and is projected from a projection lens 69in an enlarged scale. As the image display elements, a reflection-typeliquid crystal panel may be used. According to this embodiment, theemission efficiency of the light source is high, and accordingly, animage display device having high performance is realized.

In addition, as another use form of the solid state light sourceincluding a high-efficiency polarization conversion element inside theoptical system, the solid state light source may be used as a lightsource used for a head up display (HUD) that has recently attractedattention as an image display device used for a vehicle. In such a case,the image light has reflectance that is markedly different in an imagedisplay unit such as a combiner or front glass based on the direction ofpolarization, and accordingly, image display that has a high contrastratio and is clear can be performed, whereby a display having superiorvisibility can be realized.

[Fourteenth Embodiment]

In a fourteenth embodiment, a preferable drive method for a solid statelight source device will be described. Here, as visual characteristicsof human eyes for a light source, (1) Relation between lighting time andbrightness feeling and (2) Relation between lighting frequency andflicker are reviewed, and a pulse drive method not causing flicker whilereducing a drive current is proposed. As the visual characteristics ofhuman eyes, it is known that a feeling of relative brightness of lightemitted from a bright light source is different according to the lengthof the lighting time. In addition, it is known that a flicker feelingfelt by a human changes according to a lighting frequency (blinkperiod).

FIG. 19 is a diagram that illustrates a relation between a lighting timeand a feeling of brightness felt by a human. As a parameter, theilluminance value on the retina is changed. For the same illuminance, ina case where the lighting time is changed, a brightness feeling felt bya human becomes different. For example, a lighting time at whichillumination light having illuminance of 170 lux is seen to be thebrightest is 0.05 seconds. In addition, as the illuminance increases,illumination light having a shorter lighting time is felt to be bright.For illumination light of an image display device or an automotivelighting, a case where the lighting time is 0.05 seconds or less is seento be bright.

FIG. 20 is a diagram that illustrates a relation between a lightingfrequency and a feeling of flicker felt by a human. As a parameter, thebrightness (trolands) on the retina is changed. When the lightingfrequency f is in the range of 5 to 20 Hz, the flicker is large, andwhen the lighting frequency is 60 Hz or more, the flicker almostdisappears. This tendency does not depend on the brightness level

Based on the findings described above, in a case where the blinkfrequency of a light source is 60 Hz or more, a feeling of brightness isacquired without feeling flicker. By driving the solid state lightsource device under such a condition, drive can be performed for which avisually brightness feeling is acquired while suppressing an averagecurrent. In other words, by switching the drive current of the LED froma DC current to a pulse (switching between levels Hi and Low), a drivemethod, for which a visually brightness feeling is acquired with theaverage current suppressed, was considered to be present, and such amethod was tested.

FIGS. 21A and 21B are diagrams that illustrate a result of a visualevaluation of pulse drive. Here, in a case where a pulse is used for thedrive as a drive current flowing through the solid state light source,conditions in which there is no visual difference from that of a case ofDC drive, in other words, several cases where same brightness is feltwithout feeling flicker are illustrated. As parameters, in cases wherethe emission color is blue having low relative visibility (FIG. 21A, a1to a3) and cases where the emission color is green or red (FIG. 21B, b1to b3), the blink frequency f, a current ratio between levels Hi/Low,and a time ratio (duty) between levels Hi/Low are changed. In addition,a current value at the time of DC drive is set to 100%.

(a1) In a case where the emission color is blue, the drive frequencyf=50 Hz, a current ratio of Hi:Low=120%:60%, and a time ratio ofHi:Low=50:50, no flicker feeling was acquired, and a brightness feelingthat is equal to that at the time of DC drive was acquired.

(a2) In a case where the drive frequency f=65 Hz, a current ratio ofHi:Low=130%:50%, and a time ratio of Hi:Low=50:30, the same evaluationresult as that described above was acquired.

(a3) In a case where the drive frequency f=72 Hz, a current ratio ofHi:Low=150%:40%, and a time ratio of Hi:Low=50:20, a similar evaluationresult was acquired.

(b1) In a case where the emission color is green, the drive frequencyf=60 Hz, a current ratio of Hi:Low=120%:70%, and a time ratio ofHi:Low=50:50, no flicker feeling was acquired, and a brightness feelingthat is equal to that at the time of DC drive was acquired.

(b2) In a case where the drive frequency f=75 Hz, a current ratio ofHi:Low=130%:70%, and a time ratio of Hi:Low=50:30, a similar evaluationresult was acquired.

(b3) In a case where the drive frequency f=85 Hz, a current ratio ofHi:Low=150%:70%, and a time ratio of Hi:Low=50:20, a similar evaluationresult was acquired. For (b1) to (b3), also in a case where the emissioncolor is red, almost the same result was acquired.

It is estimated that the reason for the results described above is that,when light emission is performed using a current of Hi at the time ofpulse drive, almost constant brightness is visually felt to be continuedbased on the persistence characteristic of the eyes (in other words, noflicker is felt). Accordingly, compared to a case where the solid statelight source is driven using a DC current, the current efficiency can beimproved. In the example described above, the improvement factor of thecurrent efficiency was about 10% in (a1), 27% in (a2), 21% in (a3),about 5% in (b1), 24% in (b2), and 18% in (b3). As preferable conditionsfor the pulse drive, in a case where the drive frequency is 60 Hz ormore, and the current ratio between Hi:Low is 60:40 or more, also whenthe time ratio between Hi and Low is 50:50, brightness can be visuallyfelt without feeling flicker.

REFERENCE SIGNS LIST

-   1 Solid state light source device-   2 Automotive lighting-   3 Image display device-   11, 12, 13 Solid state light source assembly-   111 to 114, 121 to 124, and 131 to 134 Solid state light source cell-   21, 22, 23, 24 Multiple lens block-   211 to 214, 221 to 224, and 241 to 244 Multiple lens cell-   25, 26 Dichroic filter-   30 Polarization conversion element-   41, 42 Light shielding plate-   50 Superposition lens-   55 Luminous flux conversion mirror-   65 to 67 Liquid crystal panel-   69 Projection lens-   70 to 72 Reflector-   80 Lighting cover-   90 Light receiving unit

The invention claimed is:
 1. A solid state light source device usingsolid state light sources as light emitting bodies, the solid statelight source device comprising: N (here, N is an integer of two or more)sets of solid state light source assemblies in which a plurality ofsolid state light source cells are arranged in a matrix pattern; amultiple lens block that includes N incidence faces facing the N sets ofsolid state light source assemblies and causing light emitted from thesolid state light source cells to be incident through multiple lenscells of a matrix pattern and one emission face composing the lightincident from the N incidence faces and causing composed light to exitthrough multiple lens cells of a matrix pattern; and a dichroic filterthat is obliquely arranged on the incidence faces inside the multiplelens block and selectively reflects or transmits incident light based ona wavelength of the incident light, wherein light distributioncharacteristics and a color temperature of light exiting from theemission face of the multiple lens block to a light receiving unit arecontrolled by controlling a ratio of power supplied to the solid statelight source cells.
 2. The solid state light source device according toclaim 1, wherein the number N of the solid state light source assembliesis two, and wherein one of the solid state light source assemblies isconfigured by solid state light source cells each having green as anemission color, and the other of the solid state light source assembliesis configured by combining solid state light source cells each havingred as an emission color and solid state light source cells each havingblue as an emission color.
 3. The solid state light source deviceaccording to claim 1, wherein the number N of the solid state lightsource assemblies is three, wherein a first solid state light sourceassembly is configured by solid state light source cells each havinggreen as an emission color, a second solid state light source assemblyis configured by solid state light source cells each having red as anemission color, and a third solid state light source assembly isconfigured by solid state light source cells each having blue as anemission color, and wherein the second solid state light source assemblyand the third solid state light source assembly are arranged to faceeach other through the multiple lens block.
 4. The solid state lightsource device according to claim 1, wherein the light exiting from theemission face of the multiple lens block is split into a plurality ofpieces of light, the plurality of pieces of light are emitted todifferent areas of the light receiving unit, and light distributioncharacteristics and a color temperature of the light emitted to each ofthe areas of the light receiving unit are controlled.
 5. The solid statelight source device according to claim 1, wherein a polarizationconversion element is arranged between the emission face of the multiplelens block and the light receiving unit, and wherein the polarizationconversion element includes a polarized beam splitter film thattransmits P-polarized light and reflects S-polarized light and a phasedifference plate that converts the transmitted P-polarized light intoS-polarized light.
 6. The solid state light source device according toclaim 5, wherein a luminous flux conversion mirror is arranged betweenthe emission face of the multiple lens block and the polarizationconversion element, and wherein the luminous flux conversion mirror hasa cross-section, which has a cylindrical axis in a long axis directionof the polarization conversion element, of a concave-face shape.
 7. Thesolid state light source device according to claim 1, wherein LED lightsources of which an area of a light emitting point is 0.5 mm² or lessare used as the solid state light source cells.